The invention relates to a membrane electrolysis cell of the filter press type with one or more plate-type electrode pairs each comprising at least one non-continuous active central part, with a membrane provided for between the electrode pair(s), and with a seal installed between each electrode and membrane rim. The membrane cell is suitable for the production of an aqueous alkali metal hydroxide solution (cell liquor) as well as of halogen and hydrogen by electrolyzing an aqueous halide-bearing electrolyte (brine).
Such an electrolysis cell is already described in DE-OS No. 2809 332. According to this description the filter-press-type electrolysis cell consists of a great number of vertically arranged alternating flexible anode and cathode plates with a cation-permeable membrane installed between adjacent anode and cathode plates. Non-conductive flexible spacer plates are provided for keeping the anode plates, the membrane, and the cathode plates in place. The thickness of the spacer plates which are either coated with sealing material or consisting completely of an almost uncompressible sealing material has been chosen so that the membrane is freely located between the anode and cathode plates. As the anode and cathode plates are thin, i.e. of low surface stability, their distance across the active area towards the membrane is irregular. The consequence is a varying distance between anode and cathode plate and thus a varying surface load (voltage drop, electrochemical efficiency). Moreover, it is difficult to perfectly stretch the membrane from the cell border to maintain smoothness thereof during operation. In addition to a possible waviness of the anode and cathode plates, an imperfect smoothness of the membrane might then have to be faced so that the space between the anode and cathode plates would not exhibit absolutely uniform distances and conditions.
The object of the present invention is to create a monopolar filter-press-type cell which in comparison with those already known offers improved properties.